Carbon nanotubes are tubules of carbon generally having a length of 5 to 100 micrometers and a diameter of 0.5 to 100 nanometers. Carbon nanotubes can be composed of a number of coaxial cylinders of graphite sheets, and have recently attracted a great deal of attention for use in different applications such as field emitters, gas storage and separation, chemical sensors, and high strength composites. Recently, carbon nanotube films have been fabricated. A carbon nanotube film includes a plurality of carbon nanotube bundles that are joined end to end by van der Waals attractive force. Each of the carbon nanotube bundles includes a plurality of carbon nanotubes substantially parallel to each other. The plurality of carbon nanotube bundles joined end to end by van der Waals attractive force form the continuous carbon nanotube film. After being treated with organic solvent, the carbon nanotube film can be readily used in cables, printed circuit boards, cloths, and other macroscopic applications.
For mass production, the carbon nanotube film should be relatively long. However, the length of the carbon nanotube film is limited by an area of a super-aligned carbon nanotube array from which the carbon nanotube film is derived. In general, a diagonal length of a rectangular super-aligned carbon nanotube array is only about 4 inches. Thus, the length of the carbon nanotube film is correspondingly limited.
What is needed, therefore, is to provide a method for making carbon nanotube film that can overcome the above-described shortcomings.